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Investigating the Strut Braced Wing For Reducing Aviation's Environmental Impact
Environmental Background▰ Earth's surface temp. will increase between 1.8 and
5.8 ºC by 2100
▰ Aircraft release emissions at higher altitudes
▰ Aircraft emissions will triple by 2050
▰ Between 2016 and 2050 aviation will generate 43 gigatonnes of CO2 emissions
Design Background▰ Efficiency currently
improved with ○ Composites○ Better engines○ Small design
improvements▰ Cantilever design has been
pushed to limit
Boeing 787 Dreamliner
Introduction● The SBW design
● Consists of a strut supporting the wing
● Allows designers to create a more efficient shape
● The TBW is a more complex design to analyze
SBW and TBW Diagram
Introduction● Past Aircraft
● Has been used on past aircraft including○ Cessna 172○ Piper Cub○ Hurel-Dubois HD.31
▰ Never Implementation on a large jet aircraft
Cessna 172
Hurel-Dubois HD.31
Introduction● Current Research▰ Current research conducted by:
○ Boeing○ Nasa○ Virginia Tech○ Georgia Tech
▰ Noteworthy projects:○ Sugar Program○ Onera Program (Albatros)
Boeing Sugar SBW Test Model
Introduction
The Strut Braced Wing● utilize struts to strengthen the wing ● Allows for a higher aspect ratio● Reduces drag through:
○ Wingtip vortices (Vortex Drag)○ Thickness to chord ratio (Transonic Wave
Drag)● Vortex Drag is roughly 40% of total
drag
Wing Tip Vortex
Purpose▰ Examine drag, lift, and weight to compare the
efficiency of a traditional cantilever aircraft to a strut braced wing aircraft
▰ Discuss the broader context of this efficiency in terms of environmental impact
Research QuestionTo what extent is it viable to implement a strut brace wing design into future commercial airliners for the purpose of reducing aviation's environmental impact?
▰ Aims to fill the research gap of a direct comparison
Hypothesis
Alternative: The strut braced wing will improve the aircrafts efficiency
Null: The strut braced wing will have no effect on the aircrafts efficiency
MethodsScientific Literature Review▰ Built a larger picture of the characteristics of
SBW ▰ Focused on weight and lift▰ Used online databases
○ Research Gate○ EBSCOhost○ Google Scholar
MethodsSimulation▰ Goal is to examine drag individually▰ Used Fusion 360 program to design model
aircraft for testing▰ Used Flow Design to complete wind tunnel
analysis
Methods● Creating the Models
▰ Autodesk Fusion 360 was the cad program used
▰ Cantilever aircraft was a Boeing 737-800
▰ Three variables were tested ▰ The best of each variable were
combined into one model
Optimized SBW in Fusion 360
Cantilever Control in Fusion 360
Methods● Simulation▰ Autodesk Flow Design was
used▰ Drag coefficient and force were
measured five times▰ measurements made after the
simulation stabilized▰ All variables were held
constant
Control Cantilever Aircraft in Flow Design Wind Tunnel Simulation
Results● Sweep Angle
● Model 1 with a 20 degree sweep had the lowest average drag coefficient and drag force
model Sweep AngleAverage Coefficient Average Force
control cantilever 25° 0.17 15693.6control strut 25° 0.23 22515.8strut 1* 20° 0.21 20435.6strut 2 15° 0.21 20568.4strut 3 10° 0.23 22002.8strut 4 5° 0.246 23710.6strut 5 0° 0.24 22942
Results● Length
● Model 5 with a 130% length increase was chosen despite not having the lowest drag because realistically it would offer more lift than model 1
modelLength increase
Average Coefficient Average Force
control cantilever 0% 0.17 15693.6control strut 0% 0.23 22515.8strut 1 5% 0.21 20209.6strut 2 10% 0.22 22195.6strut 3 15% 0.24 24513.4strut 4 20% 0.24 24104.6strut 5* 30% 0.22 23141.6
Results● Vertical Thickness
● Model 5 with 75% of the controls thickness had the lowest average drag coefficient and drag force
model ThicknessAverage Coefficient Average Force
control cantilever 100% 0.17 15693.6control strut 100% 0.23 22515.8strut 1 95% 0.23 22486.4strut 2 90% 0.21 19214.4strut 3 85% 0.202 18518.2strut 4 80% 0.19 16839strut 5* 75% 0.19 16635.6
Results
● 4x10 -̂10 p value is less than .05 so optimized strut has statistically less drag than control strut
● 1.4x10 -̂13 p value is less than .05 so optimized strut has more drag than the control cantilever statistically
Model ModificationMean (drag coefficient)
Standard Deviation (drag coefficient)
Mean (drag force)
Standard Deviation (drag force)
Control cantilever None 0.17 0 15693.6 29.3
control strut Strut added 0.23 0 22515.8 58.3
optimized strut
Thickness:75%Length:130%Sweep: 20° 0.2 0 18265.2 18.91
Results● Weight and Lift
Advanced Cantilever Wing
Optimized Strut Braced Wing
Aspect ratio 9.9 13Zero fuel weight (lbs) 354,356 331,847Fuel weight (lbs) 186,332 157,977Takeoff gross weight (lbs) 540,689 489,826
● Overall decrease in weight for Strut Braced Wing aircraft
● Boeing Sugar aircraft has higher L/D ratio
Boeing 737-800 Boeing Sugar aircraftAspect Ratio 9.45 19.55Empty Weight(lbs) 90710 75600
Lift/Drag Ratio 17 24
Naghshineh-Pour, A. H. (1998, November 30). Structural Optimization and Design of a Strut-Braced Wing Aircraft. Retrieved from https://mafiadoc.com/structural-optimization-and-design-of-a-strut-braced-wing-aircraft_59b6a12a1723dddbc635a0be.html
Boeing 737-800/900. (n.d.). Retrieved from https://www.airliners.net/aircraft-data/boeing-737-800900/96Brady, C. (n.d.). Detailed Technical Data. Retrieved from http://www.b737.org.uk/techspecsdetailed.htmOuhib, A. (2014). Boeing 737-700 Drag. Retrieved from https://www.scribd.com/doc/220607389/Boeing-737-700-DragWells, D. (n.d.). Cruise Speed Sensitivity Study for Transonic Truss Braced Wing. Retrieved from https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170001025.pdf
Virginia Tech
Boeing/Nasa
Discussion● The Breguet Range Equation
● A lower drag increases range● A greater lift increases range● Lower Weight increases range● High range indicates high efficiency and less of an environmental
impact
Discussion● efficiency
▰ The SBW’s lower weight =increased efficiency▰ The SBW’s higher drag = decreased efficiency▰ The SBW’s high lift = increased efficiency▰ A higher L/D for the SBW indicates that high lift
outweighs the slight drag increase
Discussion● environmental
▰ Higher L/D ratio and lower weight indicate better efficiency and lower emissions
▰ A 30% fuel reduction is possible▰ Airlines can sustain the cost of improved
technology ▰ Replacing half of airliners would reduce CO2
emissions by 2050 roughly 6.4 gigatons
Conclusion▰ Reject null hypothesis, and accept the alternative ▰ Airlines/environment would benefit from reduced
fuel consumption of SBW▰ Further investigation of the SBW concept would be
worthwhile given the potential benefits
AcknowledgementsI would like to thank the following individuals for their assistance to this research
○ Dr. Paulo Iscold ○ Dr. Robert Breidenthal○ Dr. Arnold Deffo○ Dr. Malhotra
ReferencesAirfoil Tools. (n.d.). Retrieved from http://airfoiltools.com/search/index
Benson, T. (2014, June 12). Lift to Drag Ratio. Retrieved from https://wright.nasa.gov/airplane/ldrat.html
Boeing 737-800/900. (n.d.). Retrieved from https://www.airliners.net/aircraft-data/boeing-737-800900/96
Brady, C. (n.d.). Detailed Technical Data. Retrieved from http://www.b737.org.uk/techspecsdetailed.htm
Bhatia, M., Kapania, R., Hoek, M. V., & Haftka, R. (2009, May 7). Structural Design of a Truss Braced Wing: Potential and Challenges. Retrieved from http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.701.2665&rep=rep1&type=pdf
Coggin, J. M., Kapania, R., Zhao, W., & Schetz, J. A. (2014, January). Nonlinear Aeroelastic Analysis of a Truss Based Wing Aircraft. Retrieved from https://www.researchgate.net/publication/269249067_Nonlinear_Aeroelastic_Analysis_of_a_Truss_Based_Wing_Aircraft
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Naghshineh-Pour, A. H. (1998, November 30). Structural Optimization and Design of a Strut-Braced Wing Aircraft. Retrieved from https://pdfs.semanticscholar.org/5c5b/46c1d61e7025b790662185941584595eca1b.pdf
Ouhib, A. (2014). Boeing 737-700 Drag. Retrieved from https://www.scribd.com/doc/220607389/Boeing-737-700-Drag
Pardee, V. (2015, December). Up in the Air. Retrieved from https://www.biologicaldiversity.org/programs/climate_law_institute/transportation_and_global_warming/airplane_emissions/pdfs/Airplane_Pollution_Report_December2015.pdf
Wells, D. (n.d.). Cruise Speed Sensitivity Study for Transonic Truss Braced Wing. Retrieved from https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20170001025.pdf
Zhang, K., Ji, P., Bakar, A., & Han, Z. (2012). Multidisciplinary Evaluation of Trussbraced Wing for Future Green Aircraft. Retrieved from http://www.icas.org/ICAS_ARCHIVE/ICAS2012/PAPERS/280.PDF
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